Why do colony ships and transports disappear when you use them (sometimes)

Why do colony ships and transports disappear when you use them (sometimes)

but not other times

When you colonize your first planet your settlers get off the ship and colonize the planet. Then the ship disappears. Later, if you bring more settlers with another colony ship, the settlers can get off and the colony ship can go anywhere it wants so long as you leave 1 (1,000,000) on board to pilot, I guess. If you leave no one on board the ship can't leave orbit. If you build a colony ship with 4 colony pods you can move a billion people per trip. Not sure what happens if you use that type of ship for the initial colony. I think the ship might disappear.

I don't see why these ships ever disappear. Its a little annoying and confusing. If I don't want them anymore I can always give them away, sell them or upgrade them into something else. The game doesn't let you do that.

Similar rules apply to transports.

It also would have been nice if you build a very fast freighter it moves freight faster forever or it is replaced with the usual slow freighter but you get the initial freighter back so you can use its super speed to quickly set up another route.

Am I right in thinking the following...

A freighter earns you money each week for as long as it is moving even if it never reaches its destination. If it gets blown away, you still get paid and the ship is respawns at the beginning of the trade route for free. There is no penalty for lost ships or lost cargo. This type of thing is counter-intuitive.

fist off, whenever you colonize a new planet there will always be, at least, one colony ship being used (for the initial colony planetary improvement). that ship is simply deconstructed and its material used to establish the new colony.

the same mechanism applies whenever you invade a planet with soldiers, although if you lost a lot of your invasive force then more troopships are lost. as a rule the remaining soldiers do still have to have a place on a ship.

there are penalties to shot-down freighters:

- the mini-freighters restart at their spawnsite which naturally yields the lowest income. the more a freighter moves towards its destinated planet the more is your income.

- if a specific freighter is shot down multiple times then the route will be cancelled

if you want to establish a traderoute very fast or early you could trade for enemy scouts and upgrade them into freighters. you'll need some miniaturization & sufficient range for that, tough.

mini-freighters don't cash in on the speed of the original ship. they always move at speed 1. but they can profit from other stats. you could arm them but mostly they won't be able to withstand much pressure, and this is going to cost you maintenance. a good idea would be to place a lot of sensor mods on them so you can peak around into other terrain while the freighter moves.